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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Accessing Wind Tunnels From NASA's Information Power Grid

The NASA Ames wind tunnel customers are one of the first users of the Information Power Grid (IPG) storage system at the NASA Advanced Supercomputing Division. We wanted to be able to store their data on the IPG so that it could be accessed remotely in a secure but timely fashion. In addition, incorporation into the IPG allows future use of grid computational resources, e.g., for post-processing of data, or to do side-by-side CFD validation. In this paper, we describe the integration of grid data access mechanisms with the existing DARWIN web-based system that is used to access wind tunnel test data. We also show that the combined system has reasonable performance: wind tunnel data may be retrieved at 50Mbits/s over a 100 base T network connected to the IPG storage server.

Becker, Jeff↗
NASA NTRS2002

Data Access Technology Workshop Position Paper

This paper addresses the seven questions that were requested of attendees prior to attending the Data Access Technology Workshop that is scheduled for October 8-9,2002. Each of the questions is addressed in the following seven sections. The seven questions are: 1) What emerging technologies do you feel would best enhance user access to EOSDIS data and why? 2) How do you envision these technologies being used? How should they be used in combination with each other? 3) Can technologies be readily leveraged to achieve these results today? If not, when do you think they will be viable? 4) What investments do you think EOSDIS should make in these technologies today? Over the next 5 years? 5) What are reasonable cost expectations for leveraging these technologies as you've suggested? 6) What are the anticipated impacts on end users if these technologies are deployed, including investments required? 7) What unique researcher data access requirements need to be supported?

Hinke, Thomas H.↗
NASA NTRS2003

US Astronomers Access to SIMBAD in Strasbourg, France

During the last year the US SIMBAD Gateway Project continued to provide services like user registration to the US users of the SIMBAD database in France. Currently there are over 4300 US users registered. We also provided user support by answering questions from users and handling requests for lost passwords when still necessary. Even though almost all users now access SIMBAD without a password, based on hostnames/IP addresses, there are still some users that need individual passwords. We continued to maintain the mirror copy of the SIMBAD database on a server at SAO. This allows much faster access for the US users. During the past year we moved this mirror to a faster server to improve access for the US users. We again supported a demonstration of the SIMBAD database at the meeting of the American Astronomical Society in January. We provided support for the demonstration activities at the SIMBAD booth. We paid part of the fee for the SIMBAD demonstration. We continued to improve the cross-linking between the SIMBAD project and the Astrophysics Data System. This cross-linking between these systems is very much appreciated by the users of both the SIMBAD database and the ADS Abstract Service. The mirror of the SIMBAD database at SAO makes this connection faster for the US astronomers. We exchange information between the ADS and SIMBAD on a daily basis. The close cooperation between the CDS in Strasbourg and SAO, facilitated by this project, is an important part of the astronomy-wide digital library initiative. It has proven to be a model in how different data centers can collaborate and enhance the value of their products by linking with other data centers. We continue this collaboration in order to provide better services to both the US and European astronomical community. This collaboration is even more important in light of the developments for the Virtual Observatory projects in the different countries.

Eichhorn, G.↗
NASA NTRS2004

US Astronomers Access to SIMBAD in Strasbourg

During the last year the US SIMBAD Gateway Project continued to provide services like user registration to the US users of the SIMBAD database in France. Currently there are over 4500 US users registered. We also provided user support by answering questions from users and handling requests for lost passwords when still necessary. Even though almost all users now access SIMBAD without a password, based on hostnames/IP addresses, there are still some users that need individual passwords. We continued to maintain the mirror copy of the SIMBAD database on a server at SAO. This allows much faster access for the US users. During the past year we again moved this mirror to a faster server to improve access for the US users. We again supported a demonstration of the SIMBAD database at the meeting of the American Astronomical Society in January. We provided support for the demonstration activities at the SIMBAD booth. We paid part of the fee for the SIMBAD demonstration. We continued to improve the cross-linking between the SIMBAD project and the Astrophysics Data System. This cross-linking between these systems is very much appreciated by the users of both the SIMBAD database and the ADS Abstract Service. The mirror of the SIMBAD database at SA0 makes this connection faster for the US astronomers. We exchange information between the ADS and SIMBAD on a daily basis. During the last year we also installed a mirror copy of the Vizier system from the CDS, in addition to the SIMBAD mirror.

Oliversen, Ronald↗
NASA NTRS2005

Common Badging and Access Control System (CBACS)

This slide presentation presents NASA's Common Badging and Access Control System. NASA began a Smart Card implementation in January 2004. Following site surveys, it was determined that NASA's badging and access control systems required upgrades to common infrastructure in order to provide flexibly, usability, and return on investment prior to a smart card implantation. Common Badging and Access Control System (CBACS) provides the common infrastructure from which FIPS-201 compliant processes, systems, and credentials can be developed and used.

Dischinger, Portia↗
NASA NTRS2005

REUSABLE PROPULSION ARCHITECTURE FOR SUSTAINABLE LOW-COST ACCESS TO SPACE

The primary obstacle to any space-based mission is, and has always been, the cost of access to space. Even with impressive efforts toward reusability, no system has come close to lowering the cost a significant amount. It is postulated here, that architectural innovation is necessary to make reusability feasible, not incremental subsystem changes. This paper shows two architectural approaches of reusability that merit further study investments. Both #inherently# have performance increases and cost advantages to make affordable access to space a near term reality. A rocket launched from a subsonic aircraft (specifically the Crossbow methodology) and a momentum exchange tether, reboosted by electrodynamics, offer possibilities of substantial reductions in the total transportation architecture mass - making access-to-space cost-effective. They also offer intangible benefits that reduce risk or offer large growth potential. The cost analysis indicates that approximately a 50% savings is obtained using today#s aerospace materials and practices.

Bonometti, J. A.↗
NASA NTRS2005

Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

Wang, C.-W.↗
NASA NTRS2004

Accessing the Lunar Poles for Human Exploration Missions

The National Vision for Space Exploration calls for an American return to the Moon in preparation for the human exploration of Mars and other destinations. The surface environment of the Moon is a challenge for human operations, but recent findings from robotic and Earth-based studies have indicated that the polar regions of the Moon may offer advantages in terms of thermal conditions, availability of solar energy, and access to local resources. While accessing these regions represents a challenge due to orbital dynamics and propulsive performance, methods for accessing the regions with humans are being actively pursued, and environmental data gathering is planned through future robotic missions.

Joosten, B. Kent↗
NASA NTRS2008

Accessing and Utilizing Remote Sensing Data for Vectorborne Infectious Diseases Surveillance and Modeling

Background: The transmission of vectorborne infectious diseases is often influenced by environmental, meteorological and climatic parameters, because the vector life cycle depends on these factors. For example, the geophysical parameters relevant to malaria transmission include precipitation, surface temperature, humidity, elevation, and vegetation type. Because these parameters are routinely measured by satellites, remote sensing is an important technological tool for predicting, preventing, and containing a number of vectorborne infectious diseases, such as malaria, dengue, West Nile virus, etc. Methods: A variety of NASA remote sensing data can be used for modeling vectorborne infectious disease transmission. We will discuss both the well known and less known remote sensing data, including Landsat, AVHRR (Advanced Very High Resolution Radiometer), MODIS (Moderate Resolution Imaging Spectroradiometer), TRMM (Tropical Rainfall Measuring Mission), ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), EO-1 (Earth Observing One) ALI (Advanced Land Imager), and SIESIP (Seasonal to Interannual Earth Science Information Partner) dataset. Giovanni is a Web-based application developed by the NASA Goddard Earth Sciences Data and Information Services Center. It provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data. After remote sensing data is obtained, a variety of techniques, including generalized linear models and artificial intelligence oriented methods, t 3 can be used to model the dependency of disease transmission on these parameters. Results: The processes of accessing, visualizing and utilizing precipitation data using Giovanni, and acquiring other data at additional websites are illustrated. Malaria incidence time series for some parts of Thailand and Indonesia are used to demonstrate that malaria incidences are reasonably well modeled with generalized linear models and artificial intelligence based techniques. Conclusions: Remote sensing data relevant to the transmission of vectorborne infectious diseases can be conveniently accessed at NASA and some other websites. These data are useful for vectorborne infectious disease surveillance and modeling.

Kiang, Richard↗
NASA NTRS2003

Enhanced Multi-Modal Access to Planetary Exploration

Tomorrow's Interplanetary Network (IPN) will evolve from JPL's Deep-Space Network (DSN) and provide key capabilities to future investigators, such as simplified acquisition of higher-quality science at remote sites and enriched access to these sites. These capabilities could also be used to foster public interest, e.g., by making it possible for students to explore these environments personally, eventually perhaps interacting with a virtual world whose models could be populated by data obtained continuously from the IPN. Our paper looks at JPL's approach to making this evolution happen, starting from improved communications. Evolving space protocols (e.g., today's CCSDS proximity and file-transfer protocols) will provide the underpinning of such communications in the next decades, just as today's rich web was enabled by progress in Internet Protocols starting from the early 1970's (ARPAnet research). A key architectural thrust of this effort is to deploy persistent infrastructure incrementally, using a layered service model, where later higher-layer capabilities (such as adaptive science planning) are enabled by earlier lower-layer services (such as automated routing of object-based messages). In practice, there is also a mind shift needed from an engineering culture raised on point-to-point single-function communications (command uplink, telemetry downlink), to one in which assets are only indirectly accessed, via well-defined interfaces. We are aiming to foster a 'community of access' both among space assets and the humans who control them. This enables appropriate (perhaps eventually optimized) sharing of services and resources to the greater benefit of all participants. We envision such usage to be as automated in the future as using a cell phone is today - with all the steps in creating the real-time link being automated.

interplanetary network (IPN)↗
NASA NTRS2007

Single-Point Access to Data Distributed on Many Processors

A description of the functions and data structures is defined that would be necessary to implement the Chapel concept of distributions, domains, allocation, access, and interfaces to the compiler for transformations from Chapel source to their run-time implementation for these concepts. A complete set of object-oriented operators is defined that enables one to access elements of a distributed array through regular arithmetic index sets, giving the programmer the illusion that all the elements are collocated on a single processor. This means that arbitrary regions of the arrays can be fragmented and distributed across multiple processors with a single point of access. This is important because it can significantly improve programmer productivity by allowing the programmers to concentrate on the high-level details of the algorithm without worrying about the efficiency and communication details of the underlying representation.

James, Mark↗
NASA NTRS2010

Global Trends in Space Access and Utilization

In the not-so-distant past, space access and air/space technology superiority were within the purview of the U.S. and former Soviet Union's respective space agencies, both vying for global leadership in space exploitation. In more recent years, with the emergence of the European Space Agency (ESA) member countries and Asian countries joining the family of space-faring nations, it is truer now more than ever that space access and utilization has become a truly global enterprise. In fact, according to the Space Report 2007, this enterprise is a $251-billion economy. It is possible to gauge the vitality of worldwide efforts from open sources in today's transparent, media-based society. In particular, print and web broadcasters regularly report and catalog global space activities for defense and civil purposes. For the purposes of this paper, a representative catalog of missions is used to illustrate the nature of the emerging "globalization." This paper highlights global trends in terms of not only the providers of space access, but also the end-users for the various recently accomplished missions. With well over 50 launches per year, in recent years, the launch-log reveals a surprising percentage of "cooperative or co-dependent missions" where different agencies, countries, and/or commercial entities are so engaged presumably to the benefit of all who participate. Statistics are cited and used to show that recently over d0% of the 50-plus missions involved multiple nations working collectively to deliver payloads to orbit. Observers, space policy professionals, and space agency leaders have eloquently proposed that it might require the combined resources and talents of multiple nations to advance human exploration goals beyond low earth orbit. This paper does not intend to offer new information with respect to whether international collaboration is necessary but to observe that, in continuing to monitor global trends, the results seem to support the thesis that a global interdependent effort with all its likely complexities is an increasingly viable and pragmatic option. The discussion includes a breakdown of space missions into those of civil (scientific), military, and strictly commercial nature. It concludes that all three are robust components of a globally diversified portfolio of activities relying, essentially, on a common space industrial base and space infrastructure. As in other industries, the distribution of space industry assets and knowledge across countries and continents enables a diverse suite of options and arrangements, particularly in the areas of civil and commercial space utilization. A survey of several ongoing bilateral and multilateral space collaboration examples are provided to augment the observations regarding multinational work in space.

Rahman, Shamim A.↗
NASA NTRS2002

Global Landing Site Access Using Atmospheric Skip Trajectories

Mars direct entry, without going into orbit, does not provide global access to all landing site latitudes. Latitudes accessible via direct entry trajectories consist of a ring around the backside of the planet, centered about V infinity. Landing sites outside this ring can be achieved using a modified approach trajectory entering the atmosphere over the South Pole "aerocapture fashion" that will skip out to an altitude above the atmosphere and then re-enter the atmosphere a second time and continue to toward the North Pole. The first aerocapture maneuver is aligned to provide an exit orbit that contains the desired landing site with an apoapsis computed to provide proper ranging for the second entry. A powered maneuver is utilized during the exoatmospheric phase to remove altitude and flight path deviations due to uncertainties in the atmosphere occurring during the first entry. Three guidance schemes are required for global landing site access analysis. Aerocapture guidance was used for the first atmospheric entry, Shuttle Powered Explicit Guidance was used for the exoatmospheric maneuver, and Apollo Derived Entry Guidance was used for the second atmospheric entry. An altimeter to update the onboard navigation state after the first atmospheric entry, was required to remove accumulated deadreckoning navigation errors and achieve reasonable range errors at chute deploy.

Bryant, Lee↗
NASA NTRS2004

Advanced Propulsion Systems for Low-Cost Access to Space

NASA's Space Access Goal Ensure the provision of space access and improve it by increasing safety, reliability, and affordability. (1) The launch phase continues to be the highest risk period of any space mission. (2) Launch costs remain an obstacle to the complete utilization of space for research, exploration, and commercial purposes (3) Improving the Nation's access to space through the application of new technology is one of NASA's primary roles.

Whitlow, Woodrow, Jr.↗
NASA NTRS2013

Remote Data Access with IDL

A tool based on IDL (Interactive Data Language) and DAP (Data Access Protocol) has been developed for user-friendly remote data access. A difficulty for many NASA researchers using IDL is that often the data to analyze are located remotely and are too large to transfer for local analysis. Researchers have developed a protocol for accessing remote data, DAP, which is used for both SOHO and STEREO data sets. Server-side side analysis via IDL routine is available through DAP.

Galloy, Michael↗
NASA NTRS2013

Probing Aircraft Flight Test Hazard Mitigation for the Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS) Research Team

The Alternative Fuel Effects on Contrails & Cruise Emissions (ACCESS) Project Integration Manager requested in July 2012 that the NASA Engineering and Safety Center (NESC) form a team to independently assess aircraft structural failure hazards associated with the ACCESS experiment and to identify potential flight test hazard mitigations to ensure flight safety. The ACCESS Project Integration Manager subsequently requested that the assessment scope be focused predominantly on structural failure risks to the aircraft empennage raft empennage.

Kelly, Michael J.↗
NASA NTRS2013

Probing Aircraft Flight Test Hazard Mitigation for the Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) Research Team : Appendices - Volume 2

The Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) Project Integration Manager requested in July 2012 that the NASA Engineering and Safety Center (NESC) form a team to independently assess aircraft structural failure hazards associated with the ACCESS experiment and to identify potential flight test hazard mitigations to ensure flight safety. The ACCESS Project Integration Manager subsequently requested that the assessment scope be focused predominantly on structural failure risks to the aircraft empennage (horizontal and vertical tail). This report contains the Appendices to Volume I.

Kelly, Michael J.↗
NASA NTRS2014

Extreme Access & Lunar Ice Mining in Permanently Shadowed Craters Project

Results from the recent LCROSS mission in 2010, indicate that H2O ice and other useful volatiles such as CO, He, and N are present in the permanently shadowed craters at the poles of the moon. However, the extreme topography and steep slopes of the crater walls make access a significant challenge. In addition temperatures have been measured at 40K (-233 C) so quick access and exit is desirable before the mining robot cold soaks. The Global Exploration Roadmap lists extreme access as a necessary technology for Lunar Exploration.

Technology Portfolio System↗